Wrench



F. N`I WELSH.

WRENCH.

APPLICATION FILED SEPT- 20.I9I9.

Patented Maf.

nnHlllllllxJIIIIIlllIL AT ,E NT "O'F'Fl fCE FRANK N. WELSH, 0F CHICAGO, ILLNOS.

WRENCH.

Specicaton of Letters Patent.

Patentediar. '7, 1922.

Application led September 20, 1919. Serial No. 325,215.

To @,ZZ wzom it may concern:

Be it known that l, FRANK N. lVnLsH, a citizen of the United States, residing` at Chicago, in the county of Cook and State of lllinois, have invented a certain new and .useful Improvement in llrenches, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to wrenches.

More particularly, the invention has reference to that type of handy wrench wherein the adjustable worm is releasable from the toothed rack to permit the movable jaw to be shifted with quickness and facility in making the initial adjustment of the wrench jaws.

The main object of the invention is to provide a wrench having an extensible handle feature, whereby the effective lever arm of the wrench will automatically increase with increase of jaw opening, so as to afford a more effective leverage when operating upon large nuts or bolt heads.

Another object of the invention is to provide an improved formation of teeth for the adjusting worm and kfor the toothed rack, to the end of increasing` the eiiicieney of thc teeth and the facility with which they can bo niieshed. This particular formation of tooth is characterized by a relatively abrupt tooth face for resisting the rearward thrust of the movable jaw, but which will at the same time afford ample strength to prevent shearing of the teeth and a sufficient degree of pitch to result in quick operation.

Another object is to provide simple and compact stop means for limiting the outer swing ofthe extensible handle which carries the adjusting worm. The particular purpose of this stop means is to guide the piv otal motion of the extensible handle and to retain the extensible handle conveniently close to the shank of the wrench at all times.

In the accompanying drawing, in which I have illustrated a preferred embodiment of my invention:

Figure 1 is a side elevational view of my improvedwrench showing the shank partly broke-n away and shortened to illustrate the extensible action of the adjusting handle;

Figure 2 is a fragmentary plan view of the wrench; and

Figure 3 is an enlarged detail `view of the formation of the teeth on the worm and toothed rack.

The body of the wrench consists `of the Ordinary shank l and the integral fixed jaw member 2 on the end thereof. The shank 1 is of anydesired length, and at `its end is provided with shallow recesses in the sides thereof as indicated at 3. The movable j aw member l consists of the guide portion 5, which is slidably mounted on theshank l, and the depending jaw 6. The guide portion 5 is of conventional construction, ernb'odying a longitudinal rectangular slot extending through the same :for .engaging over the shank 1. The extent of sliding motion of thel jaw member lalong the shank 1 is limited by a pin 7 which projects from the jaw member into a longitudinal groove 7 in the shank. i

ln the upper edge of the shank l is cut a toothed rack 8, the particular tooth formation of `which l shall presentlydescribe. The adjustingworm 9, for engaging in the toothed rack 8 is rotatably mounted in an extensible adjusting handle 10. which is `pivoted to the head end of the extensible jaw member 4f, and which is adapted to be swung to or from thc shank l to disengage or enthe adjusting worm 9 in the teeth of the rack 8. Directly below the worm 9 the guide portion 5 is slotted or cut away as indicated at 11 to permit engagement of the worm 9 in thetoothed rack 8.

rlhe pivotal connection between the shiftable jaw member 4t and the handle 10 is made by bifurcating the end of the handle l() to form the two extending ears lf2- 12, which iit down over the tongue 13 projecting upwardly from the jaw member 4. A pin 15 pivotally connects the ears 12 to the central tongue 13. Further back in the body of the handle 10 there is provided a narrow vertical slot 16 in which is formed a forwardly projecting ledge or step 17. Cooperating with this .ledge or step is a lug 18 which projects up from the body of the guide portion 5 into the slot 16. This lug is formed with a rearwardly extending hook portion 19, which is adapted to engage with the ledge or step 17 to limit the outwardswing of the handle 10. rllhe spacing between the hook 19 and the ledge 17 is preferably just suthcient to allow the teeth of the adjusting worm 9 to clear the teeth on the rack 8, whereby the handle l() is always maintained sufficiently close to the shank l to permit of convenient operation with one hand.. The lug 18 lits quite snugly in the slot 1S and also functions to laterally guide the extensible handle 10 in its pivotal movement.

Between the bifurcated end of the handie` and the vertical` slot 16, the under por'` tion of the handle 10 is cut away or recessed as indicated at 21 to receive the adjusting worm 9. The adjusting worm. is rotatably7 mounted on a longitudinal pin 22. The worm recess 21 is separated from the slotted end of the handle and Vfrom the vertical slot 16 by the two transverse walls 23 and 24.. in which the pin 22 has support. rlhe pin is inserted through the slotted end of the handle,` being driven to a tig-ht fit in holes provided for same in transverse walls 23 and 24. The adjusting' handle 10 is extended out to the end of the shank 1. rlhe end of the handle 1() is reduced slightly and is shaped to conform to the `general formation of the shank 1. being' formed with shallow recesses 26 in the sides thereof to match with the recesses 3 in the shank 1. These recesses afford depressions Awhich can be readily engaged by the fingers of one hand to separate the handle from the shank.

In the operation of the wrench, the initial adjustment of the movable jaw is made by first swinging the handle 10 up to clear the worm teeth of the rock 8, then shifting the movable jaw to itsdesired position, and then squeezing the adj ustingihandle 10 down into engagement with the shank to set the worm into the toothed rack 8 and lock the movable jaw in position. A finer or tighter adjustmentl of the movable aw is made by simply manipulating the adjusting worm 9 as with an ordinary wrench. llt will be appar-` ent that after the movable aw has been slid into engagement with the nut, the amount of manipulation of the. adjusting worm will never be more than one-half turn for the reason that in closing,r the handle and shank together with the aws engaging the nut the worm teeth will always engage the rack teethV within the length of one rack tooth from the required position of the movable It will be observed that separation of the jaws of the wrench results in the projecting of the end of the adjustinghandle 1G! out beyond the end ofthe shank 1 in proportion to the extent of the jaw opening'. The greater the extent of jaw opening required for" grasping' the nut or bolt head, the greater the extent of projection of the adjusting handle 10, and consequently the more effective the lever arm of the wrench. This feature of utilizing the extensible action of the adjustable handle 10 to increase the effective leveragie of the wrench results from the location of the adjustablehandle along the upper edge of the wrench shank. in the proper use of the present wrench or any ordinary type of wrench, the aws are always engaged over the nut so as to enable the shank to be pulled downward, or toward the jaw side of the shank, so as to always force the jaws down over the sides of the nut. lt will be noted that with the present wrench, pulling of the end of the adjusting handle 10 downward or to the jaw side of the shank operates to more firmly set the worm 9 in the toothed rack 8 and to more securely lock the movable aw against shifting. It will therefore be apparent that by locatingthe adjustable handle 10 along the upper edpge of the shank there is obtained the dual function of increasing` the effective leverage of the wrench when operating` on lai-re nuts or bolt heads, and also of holding;1 the worm down in the teeth of the rack 8 more forcibly upon increase of effort applied to the end of the handle 10.

Referring` to the formation of the teeth on the adjusting worm 9 and the toothed rack S, as shown in Figure 3, it will be .noted that the opposite faces of the teeth are cut at videly different angles. The front and rear faces of the teeth on the worm 9 are sloped at different ang-les, the angle of slope ofthe rear face denoted by y being much sharper than the angle of slope of the front face denoted by an The angle 'i/ is computed so that a radial line e drawn from the piyoted center 15 will be substantially normal to the rear face of the tooth. Thev teeth on the rack 8 have, of course. the same angular relation but in reverseorder. Cutting; the rear faces of the worm teeth normal to the radial line .e enables the teeth of the worm to mesh freely and easily in the rack teeth and at the same time obtains full surface contact ofthe rear tooth faces with the rack teeth. This feature of obtaining full surface contact of the rear surfaces of the worm teeth with the front surfaces of the rack teeth is of impor ance, as it affords maximum tooth contact for receiving' the rearward thrust of the movable aw. The angle of the rear surfaces of the worm teeth is furthermore so acute to theA force line of this rearward thrust that there is practically no tendency for the tooth surfaces to cam the lever 10 outward from the shank l. The purpose in making the angle a' of the front surfaces of -the worm teethgreater than the angle t1/Tof the rear faces jis principally to add strength to the teeth by increasing the thickness of the bases or rootsof the teeth. rllhis is, of course, also applicable to the rack teeth tl. In tl e particular design shown, the angle jz/ is approximately 50 and the anglevm is approximately 8 O. It will of course be apparent, however, that these given angles are merely illustrative, and would vary with the distance of the worin from the pivotal center of the lever and with other factors of the design.

I claim:

l. In a wrench, the combination of a shank having a fixed jaw projecting laterally from the end thereof, a toothed rack in the edge of said shank opposite said fixed jaw, a shiftable aiv member slidablel on said shank, an elongated handle pivoted to said shiftable j aw member and extending` along the toothed edge of said shank, said handle having a recess in its inner edge adjacent said shank, an adjusting worm rotatably mounted in said recess, said recess defining tivo transverse walls and an outer bridge portion extending over the outer side of said worin, a pivot pin for said worm supported in said transverse walls, stop means extending between said elongated handle and said shiftable jaw member for limiting the outward pivotal motion of said elongated handle, said elongated handle being extensible from the end of said shank with the separation of the wrench jaws to increase the effective lever arm of said wrench.

Q. In a wrench, the combination of a shank having a fixed jaw projecting laterally from the end thereof, a toothed rack in the edge of said shank opposite said fixed jaw, a shiftable aw member slidable on said shank, an ear projecting from the outer side of said shiftable jaw, an elongated handle having its end pivoted to said ear, said elongated handle having` a recess in its inner edge adjacent said shank defining tivo transverse walls and an outer connecting bridge portion, an adjusting worm in said recess, a pivot pin for said worm passing through said two transverse walls, said bridge portion extending over and protecting the outer edge of said worm, the inner edge of said worm being protected by said shank, positive stop means between said shiftable jaw ano said elongated handle for positively limiting the outward pivotal motion of said handle to a comparatively small angle suffi` cient for said Worin to clear the teeth of said rack, said handle being extensible beyond the end of said shank for increasing the effective lever arm of said wrench.

3. In awiencli,tlie combination of a shank having a fixed jaw' projecting laterally from the end thereof, a toothed rack in the edge of said shank opposite said fixed jaw, a movable jaw member guided for sliding motion on said shank, an elongated handle pivoted to said movable `jaw member and extending along the toothed edge of said shank,

central tongue, an adjustable worm rotatably mounted in said handle, said adjustable worm adapted to be extended through a recess in said movable jaw member to engage in said toothed rack, and a hook stop member projecting from said movable jaw member into a recess in the body of said handle for limiting the pivotal motion of said handle away from said shank.

il. In a Wrench, the combination of a shank having a fixed jaw projecting laterally from the end thereof, a toothed rack cut in the edge of said shank opposite said fixed jaw, a shiftable jaw member slidable on said shank, a tongue projecting from said shiftable jaw member, an adjusting handle having an end pivoted to said tongue, an adjusting worm rotatably mounted in a recess in said handle on a pin in said recess, said worm being adapted to extend through an aperture in said pivotal jaw member to engage in said toothed rack, a longitudinal pin in said recess in said'handle upon which said adjusting worm is rotatably mounted, saidl handle having a recess therein, a stop projection in said recess, and a lug projecting from said shiftable j aw member and extending into said recess, said lug having a hook end adapted to engage with said stop projection to limit the outward swing of said handle.

5. In a wrench, the combination of a shank having a fixed avv on the end thereof, a shiftable jaw member slidable on said shank, a pin and slot connection between said shiftable jaw member and said shankfor limiting the shifting motion of said jaw member, a toothed rack on said shank, an adjusting handle pivoted to said shiftable jaw member, and an adjusting worm rotatably mounted on said handle and adapted to engage in said toothed rack, the angle of the rear surfaces of the teeth on said worm being substantially normal to a radial line extended from said tooth surfaces to the pivotal center of said handle.

6. In a wrench, the combination of a shank having a fixed aw projecting laterally from the end thereof, a shiftable jaw member slidable on said shank, a toothed rack in the edge of said shank opposite said fixed jaw, an elongated handle pivoted to said shiftable jaw member and extending along the edge of said shank opposite said fixed jaw, an adjusting worin rotatably mounted on said handle, the angle of the rear faces of the teeth on said worm being substantially normal to a radial line drawn to the pivotal center of said handle, the angle of the front faces of said teeth being relatively larger than that oi.' the rear faces, and Stop means between said Shiftable jaw member and said handle for limiting the outward pivotal motion 0I" said' handle, said handle being eX- tensible from the end of said shank in accordance with the extent of separation of FRANK N. WELSH, 

